Code detecting means



Dec. 18, 1945. c, VOLZ CODE DETECTING MEANS Filed July 30, 1942 F j z jb w w i mm. m Q W m v W M QBQ m a M A FL H Cr m Patented Dec. 18, 1945 IUNITED STATES PATENT OFFICE Application July 30, 1942, Serial No'.452,902

1 Claim.

My invention relates to impulse timing means of a type adapted for usein railway signaling systems.

In application Serial No. 452,894 of Frank H. Nicholson and CrawfordE.Staples, filed July 30, 1942, now Patent No. 2,331,134, issued October5, 1943, there is shown a coded signaling system in which one proceedindication is provided by a modified code employing at recurringintervals a code component which is much shorter than those employed inthe standard code. In order to differentiate between the standard codeand the modified code a relay is employed to detect the short componentin the modified code.

It is an object of my invention to provide improved means for detectinga code component shorter than a predetermined length.

A further object of the invention is to provide impulse generating meanswhich operates to sup ply to a relayimpulses of energy which areeffective to pick up the relay contacts and to cause them to remainpicked up for a period slightly longer than the short code components,but not so long as the code components of normal length.

Another object of my invention is to provide improved impulse generatingmeans arranged so that the impulses of energy supplied therefrom willnot be effective to maintain the associated relay picked up for longerthan a predetermined time regardless of variations in voltage of thesource from which energy is supplied to this means, variations intemperature, effects of rectifier ripple, relay contact wear, or shortedturns in the winding of the equipment.

A further object of my invention is to provide impulse generating meanscontrolled by a code following relay and arranged so that it will supplyenergy to the impulse detecting relay only on movement of the contactsof the code following relay from one position to the other.

Other objects of the invention and features of novelty will be apparentfrom the following description taken in connection with the accomformerprimary winding and is proportioned so that the condenser and thetransformer primary winding together form a highly damped oscillatingcircuit. When the code following relay contact opens, oscillations inthis circuit areinitiated while the period during which the impulses ofenergy supplied from the transformer to the detector relay are of avalue effective to keep the detector relay contacts picked up isdetermined.

by the frequency of oscillation in the transformer primary winding. Inaddition, when the short code component is encountered, a contact of thecode following relay cooperates with a contact of the detector relay toestablish a stick circuit for the detector relay and to also establish acircuit to supply energy to a slow release control relay. I Y

In the drawing 7 Fig. 1 is a diagram of a railway signaling systemincorporating my invention,

Figs. 2 and 3 are diagrams illustrating the types of coded energyemployed in the system shown in Fig. 1, and

Fig. 4 is adiagram of the energy impulses supplied from the timing unitto the detector relay.

Referring to F g. 1 of the drawing, there is.

, that is from left to right. The rails of the track 30' stretch aredivided by insulated joints 3 into the customary successive tracksections for signaling,

identified as section IZT, and parts of the two adjoining sections,identified as sections '1 IT and 53T, are shown. Each of these sectionshas 10- cated at the entrance end thereof a signal S governing movementof trains in the track stretch. The signals illustrated 'are of thefamiliar color light type having a green or clear lamp G, a yellow orcaution lamp Y, and a red or stop lamp R. a

The rails of each track section form a part of a track circuit to whichcoded alternating current signal'controlenergy is supplied at the exitor leaving end from the secondary of' a track transformer T1. The energysupplied to the track circuits is derived from any suitable source andmay be distributed throughout the track stretch'by a transmission line,not shown. The terminals of this source are designated BX and OK, and itwill be assumed that the energy supplied from'th'e source is alternatingcurrent'of a frequency of I00 cycles per second. 5

Each of the signal locations has associated therewith a suitable sourceof direct current, such as a primary or a storage battery, not shown,the terminals of which are designated B and C.

The particular signaling system shown in Fig. 1 is of the threeindication variety and makes use of coded track circuit energy of twodifferent types which are diagrammatically illustrated in Figs. 2 and 3of the drawing. This coded energy is provided-by code: transmitters CTwhich have, tcontactswhich interrupt the supply-circuits for theassociated track transformers a definite num; ber of times per minuteaccording to traffic or other conditions ahead. As shown the codetransmitters have two circuit making and breaking contacts 75 and 75Mwhich'are continuously actuated by a motor or other suitable mechanism;The contact 15 is operated so as to produce 75 energy impulses ofuniform length per minute which are separated by periods of equalduration during which no energy is supplied. 7

T e i eli M i iaiedeo. s, to .??11199 two cycles of energy of 75codefreguency-of'np ril? pat ern; eaeliy rele. e. .4

lWqfi@ 99?QfQQiQi f lel ep thi Ev I third code cycle in the 75M code is;modid 9 W he ef Pe od i bis-eo oyeie f fi i r ni li n t e eriods n: themi 'e e Wh t e d rat on Ol -W11? ii i l ni iee deeyele s nsree ed o thathe length of the co e cycle isthe same as the e i e l e malna ieie-"The two'types of coded energy are illustrated d i m fiee li'. n F 2isle of; he dr w n F19} 2 1 e? eiemf i. th ettero T o si lleee id areini l i eiret o h s ner y-eon: sists of recurring code cycles each .8second long, and each consisting of an 01f peripd of e second Fig. 3 isa diagram fthe therein ustr ted t is. ne ier epiisiets off w e eeeenergy o '15 c de e e ie v' o normal, pattern, while the off period inevery third code cycle is reduced to approximately one-third its n rmaen'aii are iere r p iim as eerie cycle-is increased in length so thattheoode cycle t .5 6 nd' i iioi r Ao oii iin lxif iij he15M ede a soonfiert Qeeuis Once: eve 2-4;.

ee e t Each of the tracksections includes a code following track relayTRlocated at the entrance end;

of e o e AS hown. he rac la iZTR: is of the direct current type and isconnected across the section rails through a suitable rectifier NBA.

T traek elay I Z' Ri' sas oci ted he with a decoding transformer I,2D'I%, an auxiliaryrelay l2HA,a rectifier IZRB, a timing unit IZfIU pro;vided by this invention, a detector relay IZTRA, anda slow releasecontrolrelay IZHB.

The timing unit IZ'I'U includes atransformer l ZTA, a condenser IZQ,anda rectifier! ZRC. The

condenser IZQ is connected across the end term e e h Pr ary-wi dinoithetra s m IZTA. A circuit controlled by. contacts of the relays lZTRA and! ZTR-is provided for establishingconnection fromterminalB ofthe source of following operation of its contacts. As' a result ofmovement of contact l5 between its two positions, the two portions ofthe primary winding of transformer IZDT are alternately energized andenergy is induced in the transformer secondary winding from which it issupplied through the rectifier IZRB to the relay IZHA so that thecontacts of this relay are picked up. The relay IZHA is of a typethe'contacts of which. are slow in releasing so that they remain pickedup during the intervals between the impulses of energy supplied thereto.

Since relay IZHA is picked up, its contact l6 establishes the circuit ofthe contact 15M of code transmitter l-ZCT so that energy of 75Mfrequencyissupplied-tn the track transformer I ITT.

On movement of track relay contact IE to its picked-up positionat a timewhen the contacts of relay I 2TRA are released, energy is supplied tothe primary winding of transformer I2TA over he, ci ui hich. is traced-T?! rm nal: B hroes-{hr ront. co ta t. oi reole re a 15?, wire l9, backcontact 20 of relay IZ'I'RA, and the 2 PPK iQ LQfi, he primar nding i tan o r 55A o: e mina At thi time t ond nser. 29 lior esib e i rey upp ovhe eiiiq iii raced; -FQQIQIm Qa Be ieh. ront con a t. iila l tli aw re.35 an ok o taot 2H0. ofrelay IZTRAJ to one. terminal of the ondenser 91Whi e lie he erm oi t conde se s: eoeneeted throu the 'w r portionQithe. ra or r:i r iiiaryfw iiii e t rminal C he; ql i er. he n iiota ooi his t i o the ans ormer p imar w ndin s uch that flow of; energy inthecircuitof; the, condenseriiis d layed ith. he i ill li itw a n the ta k;

relay co ntacts is minnniaed.

T p r portion of the transformer primary winding is preferably formed.from a, relatively ew i insioirhea yiwire so that; on estabiismnent o heci uit oi thiswi d na current Qfrelatively; i h. a ue u oklyuild pinthewinding nd; nsures-that, he ra sformer core is saturated with flux. Thelowerportion of the transformer Pr mar w nd n ist reieiab y; formed of arelai y a e m er ofr urnso fi e Wire so that t e u ne Jittlespace-soothe r ns or er re yet has hi h: e. o i h-.' i. si ioia oe t ncn properly- W t a ondens r o r mell apa t Onv t e siipp yeoener y to theprimary ind-tv ing oftransiormen IZT A an impulse of energy is ndl fifidnth t ansformer secondary, u e e y s ot: ppl d th refr morrelay; IRA ascon: tact 22-of the trackrelay l,;2 'I}R is pickedup.

' On. releaselof'thetraok rel y ts, ntact 8 interrupts the circuitstracedabove, for supplying. energy to the, upper, portionof the primarywind is tr nst r-mer Q'BA. and. o ndenser -9, While. its contact; 2;2;es ta]o1 i s hes the circuit to sup p y ener y f om. eseooiidor wi dinransrm r 2, A toi' .sr *TR.

On release, of; track relay contact I 8% andinterruption-0t thesi.1pp1yof=1ene y to thetr siormer primary winding and to the condenserIE-Q, the ux n e rans o m r oor.e. t niie o, co a s whiletheener yStored; in the condenser lzQ dis charges through the transformer primaryWind} ing. The collapse of -the fluxin the transformer core andf'theflow of; energy} from the Condenser through the transformer primarywinding cause.

oscillations to t eset in the primary circuit bic l ii urn, QQWQ W t V rneiei e i ee ile n in Th r e twe tme co ar 1 to be, inducedv in. the.

- eoiz e te iie t e ni ele i the rectifier IZRC, while one outputterminal of this rectifier is connected to terminal C and thus to oneterminal of the winding of relay IZTRA. The other output terminal of therectifier is connected through back contact 22 of relay IZTR to theother terminal of the relay IZTRA; Accordingly, on release of the trackrelay IZTR energy is supplied from the secondary winding of transformerl2TA through the rectifier I2RC to the relay IZTRA and its contacts pickup.

The condenser I2Q, and the primary windin and the core of transformerIZTA are selected and proportioned so that on opening of track relaycontact I8 the condenser and the transformer primary winding form ahighly damped oscillating circuit, and the energy flowing in thiscircuit causes energy to be induced in the transformer secondary windingfrom which it is supplied through the rectifier IZRC to the relay I'ZTRAand maintains the contacts of this relay picked up. However, because ofthe highly damped characteristic of the oscillating circuit, theimpulses of energy induced in the transformer secondary winding rapidlydecrease in value and Y $0011 are reduced to such an extent that theenergy supplied to the relay IZTRA is ineffective to maintain the relaycontacts picked up.

The various parts of the timing unit TU and of the relay TRA areselected and proportioned so that the energy supplied from the timingunit to the relay is efiective to keepthe relay contacts picked up for aperiod longer than the short oil period in the 75M code, but will notkeep them picked up for a period as long as the off periods in the '75code, or the off periods of normal length in the 75M code.

Accordingly, when the track relay releases, energy is supplied from thetiming unit I2TU to the relay IZTRA and the contacts of the relay IZTRApick up and its contact 20 interrupts the I8 of track relay IZ'I'R doesnot establish the circuit for supplying energy to the timing unit I2TUsince contact 29 of relay IZTRA is picked up, but does establishcircuits to supply energy to relays l2'IRA and IZHB. The circuit forsupplying energy to relay IZTRA is traced from terminal B through frontcontact ill of relay IZTR, wire [9, front contact 29 of relay IZTRA, andwinding of relay I2TRA to terminal C. The circuit for supplying energyto relay IZHB is the same as that for relay IZTRA up. to the frontcontact 23 of relay IZTRA, and is traced therefrom through front contact22 of relay TR, and thence through winding of relay IZI-IB to terminal0.

The energy supplied to the relay IZ'I'RA keeps the contact of this relaypicked up so that it maintains the'circuit for supplying energy to relayI2HB throughout the long on period following the short off period in the75M code. The energy supplied to relay IZHB during this long on periodpicksup the relay contacts, if they are not already picked up, while itenergizes the relay sufiiciently that its contacts will remain picked upthroughout the intervals between the long on"periods in "the '75M'code.

--On releaseofthe track relay following the long on period in the 75Mcode, contact 18 inter-- rupts thes'u'pply of energy'to relays IRA andIZHB, while contact 22' additionally interrupts the circuit ofrelayIZHB. At this time the contact of relay IZTRA releases, but becauseof the slow' energy is not supplied to the relay IZTRA at this time andits-contacts remain released.

On picking up of the track relay contacts in response to the first onperiod in the code following the long on period, contact I8 establishesthe circuit'including back contact 20 of the relay IZTRA for supplyingenergy to the timing unit I2TU so that on the subsequent off period inthe code, energy is supplied from the timing unit to the relay IZTRAover the circuit including back contact 22 of the track relay.Accordingly, the contact of relay IZTRA picks up, but it releases beforethe end of this off period in the code so that during the next picked-upperiod of the track relay contacts energy is again supplied to thetiming unit I2TU.

The next off period in the code is the short off period, and on releaseof the track relay contacts energy is again supplied from the timingunit IZTU to the relay I2TRA and the contact of relay IZTRA picks up,while the track relay contacts pick up before the contact of relay IZTRAreleases. Accordingly, energy is supplied to relay IZTRA over its stickcircuit, while energy is also supplied to relay I2HB so that this relayis energized to maintain its contact picked up until the next long onperiod in the 75M code. From the foregoing it will be seen that thetiming unit IZTU and the relay IZTRA together provid means for detectingthe short off periods in the 75M code. The timing unit I2TU suppliesenergy of substantially fixed value to the relay IZTRA, and this energyis of such value and duration as to maintain the contacts of the relayiZTRA picked up throughout a short off" period, but not throughout anoff period of normal length. Accordingly, when the track relay contactspick up following a short off period in the code, the contacts of relayI2TRA are still picked up and energy is supplied to relay IZTRA over itsstick circuit and is also supplied to relay I2HB. When the track.relaycontacts pick up following an 0 period or normal length, the contacts ofrelay |2TRA are released and hence energy is not supplied over the stickcircuit for the relay, nor to relay IZHB, but is supplied to the timingunit so that it is prepared to supply energy to relay IZTRA on releaseof the track relay contacts. The relay IZHB, therefore, is energized.during each long "on period inthe 75M code, and remains picked up in theintervals between these periods.

Since the contacts of relays I'll-IA and IZHB argpicked up, energy issupplied to the green lamp G of signal |2S over the circuit which istraced from terminal B through front contact 25 of-relay I2HA, frontcontact 26 of relay "HE, and lamp G to terminal C. Accordingly, thegreen lamp of signal I2S is lighted so this signal displays its clearindication.

-When a train moving in the normal direction 50f trafiic enters sectionI2T, the trackrelaylTI'R icn ne testo t red c1: stop i dication: and Zcede-1 freq ency a b sure equ pm nt 3 .r 1;

seed cnteetse sun 1 Duringhe; rzi

h i cuitl r-suae r a re eased, and; en r y s up lied amp, Yflifisisua sier eci sced, fr m minal: B.- hrou h.

ofrel-ay: 121%; back co tact. 26 n y lcw amp-Y of s n l; [2s

Wh n, th rain; adv nces-far en ugh n vacate. ect on. Isl-L the eq1.ir;Incl-1tv for hat: section oper es: to; cau e, ignal: I tsrto d splayts y low ndi ation andto cause ener y: of: 75M'c0def1'ea quenctobasupplied-torsectionlfif. When this energy; is;supp1ied to trackrelay; HTR; energycontinues to; be supplied;- through: the trans: formerMDT- tohthe relay REA soztha-tethe cont-r tenets of this relay remainpickedup-r In additipn; when. the. track; relay IZTR; responds to:energy; of" 715M code frequency, energy--is-.sup-. plied: to the: relayI=2HB during the. long 011 periodslinthis; code, aslexplainediabove, andthe contactsof. this-.rrelay. are maintained picked up sothelsignal:IZS. displays its; green. or clear. inn-s dication, V

The. timing.- means provided by this invention is arranged so that itwill accurately detectthe short on period in the75M code andso thatathe-detector relay: I2TRA will: not falselysrespond to. intermittentmovement ofr-theltrack relaywonl-m tacts.

The track relay contact Ht, when picked up, establishes the circuit tosupply energy: to, the timing: unit, Whilfi the track relay contact 22whenreleased, establishes the circuit tov supply energy fr0m thetiming-unit to-the detector re lay. Accordingly, if whenthetrack-relaycontactsare: picked: up; the supply" of energy' to the track relay ismomentarilyreduced or inter-l rupjed' so that the trackrelay-contactsvibrate withoutmoving all: of-Athe wayao theinreleased o relayoperatingcondition The transformer IZTA.

is designed so: that; its core, is quickly saturated, when the voltageofthe energy supplied thereto is at; the, lowest: value at; which theequipment;

is; required to operate, Accordingl the. energy stored in the,transformer is substantiallycomstant regardless of voltage variations.Some;- encrgy is also stored in the condenser IYZQ, and

while the amount, of this. energy affected by:

variationsin the voltage of the-source of energ r the amountof'energystored in the condenser-is: relatively: small compared to thatstored in the transformer so that variations in the energy stored in thecondenser have substantially. no eifect on the: operation of the unit.

On release of contact; l8. and interruption of the-supply.- of energ tothe unit TU, the con-.

denser Q and the primary winding of trans.- former TA form a highlydamped oscillating circuit. On each oscillation of the current in thetransformer primarywinding'an impulse: of en-- ergy is induced in thetransformer secondarywinding and may be supplied therefrom tothe relayiZTRA. Because of the highly damped. nature of the circuit of thecondenser and the;

between the instant contact l8: of'trackrelay TR:

opens to interrupt the supply of energy, to the timing unit, and theinstant at which contact 22 closes to establish the circuit tosupplyenergy; from the: timing unit to relay TRA. In thisntime, intervalthe first oscillation in the circuit of the timing unit is started andthe voltage; of the; energysupplied to the circuit of the. relay; TRA isbuilt up to a high value at the instanttthati: contact 22 closes tocomplete the circuitofther relayTRA. The first impulse of energysupplied to therelay 'IRA greatly exceedsthe'value neces: sary to pickup the relay TRA. The firstim:

pulse'of energy. supplied" to relay TRA soon ter- I minates andasecondimpulse of energyis sup plied thereto. The second impulse of energdoes;

not reach as high a value asthe first, but:it,c on

siclerablyexceeds the release value ofrelay.-'I RA so the contactof'thisrelay remainspiekedup.

There isla short period at: the: endjofthe impulse and the start of thesecond impulse.dur-. ing which the energy. supplied to relay-is below.its release. value, but the rectifier- IZBIQ has sary to maintain therelay contacts picked up. Accordingly, the contacts of relay TRA releaseshortly after the second impulse of energy decreases, below the releasevalue of relay TBA.

The effect of the damping on the oscillations in the timing unit is so.great that while the second impulse of energy supplied to relay TEA iswell above the release value of relay TBA, the third impulse of energyis well below the release value of relay TRA. Furthermore, the waveshapes of the first and second impulses of energy supplied to relay TRAare such that these impulses eXceed the release value of relay TRA mostof the time. Accordingly, changes in the amplitude of the oscillationsin the timing unit have little efiect on the time during which theenergy supplied to the relay TRA exceeds the value necessary to keep therelay contacts picked up. Instead the time during which the energysupplied to relay 'IRA exceeds the release value of the relay isdetermined principally by the frequency of the oscillations in thetiming unit. The frequency of these oscillations is determined by thevalues of the condenser Q and the inductance of the transformer primarywinding, and is substantially unaffected by variations in operatingconditions.

On movement of the track relay contacts toward their released positioncontact i8 interrupts the supply of energy to the timing unit and theoscillations in the circuit of this unit start. A short time afterwardscontact 22 closes and establishes the circuit to supply energy from thetiming unit to the relay TRA. The length of the time from the instantfront contact l8 opens and the instant back contact 22 closes isdetermined by the distance the relay armature must move, and this isaffected by adjustment of the relay contacts and by wear on them.However, during this time interval [there is no load on the timing unit,and accordingly there is little clamping effect on the oscillations inthe timing unit, while there is little loss within the unit self.Accordingly, wear on the track relay contacts, and consequent increasein the time between opening of contact i8 and closing of contact 22, halittle eiiect on the energy supplied from the timing unit to relay TRA.

The timing unit also operates so that short circuiting of some of theturns of the transformer primary winding will not objectionably increasethe picked-up periods of the relay TRA. If some of the turns of thetransformer primary winding are short circuited, the rate of theoscillations in the circuit of the transformer primary winding will bedecreased, and the length of each oscillation will be correspondinglyincreased. However, the short circuited turns impose a load on thetransformer and reduce the energ supplied to the relay TBA, It has beenfound that if enough turns of the transformer primary winding are shortcircuited to materially decrease the rate of oscillations in the circuitof the transformer, the value of the impulses of energy supplied to therelay TRA will be reduced so much that the second impulse of energysupplied to relay TRA is ineffective to maintain the relay contactspicked up. I

Although I have herein shown and described only one form of apparatusembodyin my invention, it is understood that various changes andmodifications may be made therein within the scope of the appended claimwithout departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

In combination, a code following relay having contacts movable between afirst and a second position, means for supplying to said relay codedenergy in which the code components are at times of one length and atother times are of a shorter length, a device including a. windingmounted on a magnetic core and a condenser and arranged to form ahighlydamped oscillating circuit, a source of unidirectional ener y, meansincluding a contact of said code following relay closed when the relaycontacts are in their first position to supply energy from said sourceto said device to store up energy therein on movement of the relaycontacts to their second position to disconnect said source from saiddevice to cause current to oscillate in said device, a detector relayhaving contacts which occupy a picl ed-up position only when energy inexcess of a predetermined value is supplied to the, relay, and meansincluding a contact of said code following relay closed when the relayconare in their second position and responsive to oscillations in saiddevice for supplying to said detector relay energy the value of whichvaries in accordance with the magnitude of the oscillations in saiddevice, said device and said detector relay being selected andproportioned so that the energy supplied to said relay as a result Ofoscillations in said device exceeds said predetermined value for aperiod longer than a code component of said shorter length but not for aperiod as long as a code component of said one length.

CARL VOLZ.

